Geographic Range

Sunda slow lorises (Nycticebus coucang) live mainly in Indonesia (Sumatra, Batam and Galang in the Riau Archipelago, and Pulau Tebingtinggi and Bunguran in the North Natuna Islands), Malaysia (on the Peninsula and the island of Pulau Tioman), the southern peninsular area of Thailand (from the Isthmus of Kra southward) and throughout Singapore. (Nekaris and Streicher, 2008)

Physical Description

Sunda slow lorises range in length from 27 to 38 centimeters and weight from 599 to 685 grams. They have a mostly white stripe between their eyes, beginning near the top of their forehead and descending to the end of their nose. They usually have light brown pelage with a darker-colored stripe running down their back. Thick fur hides their ears. Their highly-reduced (to a stump) vestigial tail is also hidden underneath their fur. Their eyes are large due to their primarily nocturnal activity. Their second digit is reduced; their hands act as powerful clamps for grasping. Male and female Sunda slow lorises do not vary by color, size or weight, in general, there is little to no sexual dimorphism displayed by this species. They have a toothcomb and six procumbent teeth on their lower jaw, consisting of the lower incisors and the canine teeth. Lorises use their toothcomb to scrape off gum when foraging, and rarely use their toothcomb for grooming (a common practice among other primates with toothcombs). Like other slow lorises, these animals have wet noses, round heads, small ears hidden in thick fur, a flat face and large eyes. (Ankel-Simons, 2007; Choudhury, 1992; Groves, 2001; Martin, 1979; Nekaris, et al., 2008)

Reproduction

Males track females in estrus; however, females initiate the act of copulation. To initiate, the female hangs from a branch within sight of the male, often vocalizing to draw further attention. The male then holds the female and the branch, while simultaneously copulating with her. Urine-marking may also be used by the female to solicit mating. The male may create a mating plug following copulation. (Fitch-Snyder and Jurke, 2003; Izard, et al., 1988; Zimmermann, 1985)

Slow lorises have been observed in groups of up to six conspecifics including a female in estrus and five males. This may suggest a promiscuous mating system, where females mate with more than one male. No further evidence for polyandrous mating has been recorded, but the possibility is likely given their mating structure. (Wiens, 2002)

Sunda slow lorises are polyestrous, having many periods of sexual receptivity during a year. Their estrus cycle lasts 29 to 45 days, with most copulations occurring in succession. Their gestation period averages 188 days, after which one offspring is born, although twinning has been observed. Offspring are weaned between three and six months of age. Sexual maturity is reached between 18 and 24 months of age in females, and can be reached as early as 17 months in males, although males typically become sexually mature around 20 months. (Fitch-Snyder and Jurke, 2003; Izard, et al., 1988)

Only females care for their young. Before and during weaning, females lick their young, covering them in toxic oil, so the young may be protected while the female leaves to forage. Females also provide an example from which the young will learn to move through the trees. (Izard, et al., 1988; Wiens and Zitzmann, 2003)

Lifespan/Longevity

In the wild, this species average life span is 20 years, including one individual that survived 22 years. Their average life span in captivity is 24 years, including the longest-lived individual on record, which survived 25.8 years. In captivity, Sunda slow lorises tend to be more stressed and aggressive, which may result in a shorter life span of 12 to 14 years. (Daschbach, 1983; Human Ageing Genomic Resources, 2013)

Behavior

Sunda slow lorises move slowly through trees on all four limbs, typically with three limbs attached to support at any given time. Their locomotion is similar to crawling. They move with little noise or change in speed. At times they may hang below a branch by one or both feet for long periods. In captivity, movement includes quadrupedal locomotion (24%), climbing (21%), suspension (including cantilevering) (29%), bridging (23%) and other forms of locomotion (3%). (Erhlich and Musicant, 1977; Gebo, 1987; Ishida, et al., 1986; Rigel, 2004; Wiens, 2002)

Sunda slow lorises are mainly solitary, spending only 8% of their active time near other individuals. In cases of home range overlap spatial groups form, usually consisting of one male, one female and 1 to 3 younger individuals. Interactions among spatial groups are mainly positive: allogrooming, following, pant-growling and click-calling are all observed. Despite this, only 3% of active time is spent within the spatial group. This evidence may suggest a monogamous social system, though polyandrous activity has been observed. (Gron, 2013; Wiens and Zitzmann, 2003; Wiens, 2002)

Home Range

Upon witnessing a conspecific inside their home range, or when entering the home range of another individual, this species generally shows no visible reaction; home ranges do not appear to be defended. Although Sunda slow lorises commonly stay within their own home range, they show no hesitation in entering another individual's home range or in having others enter their own home range. The individual's range serves as a general ground for activity, with no actual attachment to the range except by habit. (Gron, 2013; Wiens, 2002)

Communication and Perception

Adults exhibit eight distinct calls of one of two types: contact calls (whistles, short keckers) and aggressive or defensive calls (long keckers, grunts, snarls, screams). During mating, females may whistle when in visual contact with a male, in order to draw attention. No alarm calls are used for signaling predators, as crypsis is the most common response for avoidance. Infants may exhibit squeaks or clicks when disturbed. Young individuals especially, but also adults, use ultrasonic vocalization when exploring new environments or during complex handling (locomotion). (Daschbach, 1983; Zimmermann, 1985)

Olfactory senses play a central role in species interaction, with uses ranging from alerting others of identity, to physical state and even positioning of the individual. Their elbows contain glands that exude oils, which are licked and spread by the individual to communicate position and status. This species also uses perineal rubbing to deposit urine combined with the oil, from a separate gland on their anus. When locating the scent of another, the individual will usually rub its face on the surface where the scent was found. The oil is poisonous, with enough power to kill an adult human if not treated properly. Stressed individuals may grin, baring their teeth to present aggression or fear, but they may also grin during play. (Gron, 2013; Hagey, et al., 2007; Rasmussen, 1986; Tenaza and Fitch, 1984)

Food Habits

Sunda slow lorises are dietary generalists, feeding on saps, gums, nectars, stems, fruits and occasionally arthropods such as spiders and insects. They have also been observed consuming snails and bird eggs. Roughly one third of their diet is saps and gums, another third consists of nectar and nectar-producing plants and approximately one fourth of their diet is fruit. The remainder of their diet consists of random items, such as snails and eggs. Despite a very slow metabolic rate, this species has a high-energy diet, most likely due to the energy costs of detoxifying certain ingested plant compounds. (Wiens and Zitzmann, 1999; Zimmermann, 1985)

Predation

All slow loris species, including Sunda slow lorises, produce a toxin in glands on the insides of their elbows. Using their toothcomb during grooming, the toxin is spread across their fur. If threatened, lorises will roll into a ball, leaving nothing but toxic fur exposed to the predator. Lorises may also roll into a ball and drop from the trees if the predator is arboreal. They may also bite, though this is very rare compared to their more passive defenses such as crypsis. Their predators include reticulated pythons, changeable hawk-eagles and Bornean orangutans. (Alterman, et al., 1995; Tenaza and Fitch, 1984; Wiens and Zitzmann, 1999; Wiens and Zitzmann, 2003)

Ecosystem Roles

Sunda slow lorises have no major effect on their immediate environment. As a consumer, they affect populations of flowering plants (consuming nectar and fruits), birds (consuming eggs) and other taxa (namely insects and mollusks). As prey, they serve as food for larger taxa, such as reticulated pythons and Bornean orangutans. Sunda slow lorises do not defend their home range or territory, allowing individuals of the same species and other species to pass through uninhibited. (Hagey, et al., 2007; Wiens, 2002; Wiens, et al., 2006)

Conservation Status

This species is greatly threatened by the pet trade. To prevent injury for owners, their teeth are often removed, which almost always (90% of the time) leads to infection and painful death. Once their teeth have been removed it is also impossible to re-introduce them into the wild. Because of extreme mortality rates, mainly due to infection, improper nutrition and heightened stress, the trade is further inflated by the constant need for replacements. Likewise, human developments continue to encroach on their habitats. ("Notification to Parties: Consideration of Proposals for Amendment of Appendices I and II", 2007; Nekaris and Streicher, 2008)

The species is also threatened by gathering for illegal traditional medicine. They are also killed as a crop pest. In addition to poaching, severe habitat loss and degradation over large areas of their range have caused large population declines, despite the species being more adaptable to human habitats than most other primates in the region. The resulting fragmentation has restricted species dispersal as they depend on continuous canopy cover to move from tree to tree. (Nekaris and Bearder, 2007; Nekaris and Nijman, 2007; Schulze and Groves, 2004)

Other Comments

The etymology of their common name, Sunda slow loris, refers to the Sunda Islands, a group of islands in the western part of the Malay archipelago where they are found. Another common name for the species is the greater slow loris. The specific name, coucang, derives from kukang, their common name in Indonesia. They are commonly known as malu-malu, meaning "shy" in Indonesian, and also as bukang or Kalamasan. In the vernacular they are sometimes called Kuskus because local people in Indonesia do not distinguish between the slow loris and Cuscus, a group of Australasian possums. In Malaysia, they are sometimes known as kongkang or kera duku; kera is Malay for monkey while duku is the fruit-bearing tree Lansium domesticum. In Thailand, they are called ling lom, which translates as "wind monkey". ("Notification to Parties: Consideration of Proposals for Amendment of Appendices I and II", 2007; Nekaris and Streicher, 2008; Schulze, 2004)

Contributors

Glossary

acoustic

uses sound to communicate

arboreal

Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

drug

a substance used for the diagnosis, cure, mitigation, treatment, or prevention of disease

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

female parental care

parental care is carried out by females

fertilization

union of egg and spermatozoan

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

frugivore

an animal that mainly eats fruit

herbivore

An animal that eats mainly plants or parts of plants.

insectivore

An animal that eats mainly insects or spiders.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nectarivore

an animal that mainly eats nectar from flowers

nocturnal

active during the night

omnivore

an animal that mainly eats all kinds of things, including plants and animals

oriental

found in the oriental region of the world. In other words, India and southeast Asia.

pet trade

the business of buying and selling animals for people to keep in their homes as pets.

poisonous

an animal which has a substance capable of killing, injuring, or impairing other animals through its chemical action (for example, the skin of poison dart frogs).

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

scent marks

communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them

scrub forest

scrub forests develop in areas that experience dry seasons.

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

tactile

uses touch to communicate

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

ultrasound

uses sound above the range of human hearing for either navigation or communication or both

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

year-round breeding

breeding takes place throughout the year

References

Management Authority of Cambodia. Notification to Parties: Consideration of Proposals for Amendment of Appendices I and II. Unknown. Netherlands: CITES. 2007.

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The Animal Diversity Web is an educational resource written largely by and for college students. ADW doesn't cover all species in the world, nor does it include all the latest scientific information about organisms we describe. Though we edit our accounts for accuracy, we cannot guarantee all information in those accounts. While ADW staff and contributors provide references to books and websites that we believe are reputable, we cannot necessarily endorse the contents of references beyond our control.

This material is based upon work supported by the
National Science Foundation
Grants DRL 0089283, DRL 0628151, DUE 0633095, DRL 0918590, and DUE 1122742. Additional support has come from the Marisla Foundation, UM College of Literature, Science, and the Arts, Museum of Zoology, and Information and Technology Services.